Conventional radiation therapy using X-rays or gamma rays, which is a widely used treatment method, provides a high dose of radiation to a human body regardless of the depth from the skin surface, and thus the radiation affects normal cells before it reaches a lesion. On the other hand, particle beam therapy which uses proton beams or heavy charged particle beam is characterized in that a dose of the particle radiation reaches its peak at a predetermined depth from the skin surface of a human body, and thus enables intensive irradiation of a lesion while minimizing damages of normal cells, which is an effective treatment method.
However, a particle beam therapy system is a large-size apparatus that irradiates a lesion with high energy charged particle beams emitted from a large-size accelerator. Thus, the arrangement of equipment relating to the beam delivery system is determined uniquely, and a radiation port including a radiation aperture for emitting particle beams cannot be arranged arbitrarily.
A diagnostic 3D imaging unit, which is typified by a CT device, is preferably used for diagnosis of positioning of a lesion having a three-dimensional shape. However, it is difficult to arrange the particle radiation port so as not to interfere with the large-size diagnostic 3D imaging unit. Accordingly, in order to employ diagnosis by the diagnostic 3D imaging unit for the particle beam therapy, the following procedure has been necessary: a lesion is positioned in a treatment table of the diagnostic 3D imaging unit; a treatment plan is prepared based on the positioning; a subject is moved to a treatment table of the particle beam therapy system; the lesion is positioned again; and treatment is then performed. Thus, the positioning accuracy has been low.
Described below is an example of a conventional treatment table (couch) system which enables positioning using a common couch without requiring a subject to move between different treatment tables of a plurality of apparatuses such as a diagnostic apparatus and a treatment apparatus.
This system is provided with a couch used in common for a plurality of medical apparatuses, means for supporting the couch so as to be moved in one direction of three-dimensional directions, and means for controlling the movement of the couch in the one direction thereby to individually position a subject to an isocenter of each of the plurality of medical apparatuses. The positions of the respective isocenters of the plurality of medical apparatuses, with respect to the remaining two directions of the three-dimensional directions, are set identical to one another (see Patent Document 1, for example).    [Patent Document 1] Japanese Laid-Open Patent Publication No. 2005-52308